利用陽極氧化鋁製作金屬介電超材料及其光學特性量測

Abstract

陽極氧化鋁因為具有奈米級、孔洞規則性排列等特質，而被廣泛運用在各種材質的奈米線製程，而近來人們發現利用奈米金屬顆粒鑲嵌在氧化膜裡，出現一些有趣的光學性質，如負向折射率等等。 本論文利用二次陽極氧化技術，以及不同電解液，成功製作出100nm、60nm孔洞空間分布的陽極氧化鋁，並利用不同的參數控制，探討各種生長條件，以符合後續實驗目的。並且在後續使用電化學方法在孔洞內沈積銀金屬顆粒，觀察在不同氧化膜厚度、金屬線填充度其光學反應的。 首先在反射率表現上，包含銀的氧化膜，在波長小於、等於可見光下，反射率大約都是在10%以下，但在波長325nm出現了一道波峰，原因來自於銀的表面電漿共振，並且在角度變化上激發特定波峰。 另外在紅外光以上的波段出現了干涉的現象，並隨角度改變波峰之間的相位差。 包含銀的氧化膜，在穿透率及吸收率上，都出現了以波長做為分隔線的兩種材質行為，推測原因可能與氧化膜孔洞大小有關，並且也觀察到表面電漿共振有力的證據，如強放光、低吸收等行為，在光學行為上如同特定光的通道一般。

Owing to the characteristics of regular arrangement pore structures in nanoscale, anodic aluminum oxide (AAO) has been widely used in the process of nanowires of a variety of materials. Recently, it was uncovered that the use of metallic nanoparticles embedded in the oxide film resulted to some interesting optical properties, such as negative refractive index, light-induced conductivity. In this thesis, by combining the secondary anodic technology with different electrolyte, we successfully fabricated spatially distributed nanopores with sizes of 100nm and 60nm in AAO. Silver metal particles were deposited subsequently in the pores on the AAO templates to form metallic nanowires using the electrochemical methods. Dependence of the optical response on degree of metal filling, thickness of oxide film, and metallic wire were reported. The reflectance spectra of AAO films with silver particles show a reflectance of less than 10% at visible and UV. Resonance peaks are observed due to the surface plasma resonance of the embedded metallic nanowirs when the measurements were taken at various the angles. Interference phenomenon was observed below the near infrared due to the multiple reflections. The phase of the interference patterns also varied with the angles of the incident light. For oxide films containing silver nanowires, the transmittance and absorption behave distinctively for wavelengths above and below 500 nm. At wavelengths above 500 nm, the films shows low reflectivity and exhibit several strong surface plasma resonances. We speculate that this may be related to the pore sizes of the oxide films.